From 0b47a171a13f041f4dadf5ab8f55d46c634e3dd0 Mon Sep 17 00:00:00 2001
From: Derrick Brashear <shadow@dementia.org>
Date: Fri, 9 Feb 2007 01:30:31 +0000
Subject: [PATCH] STABLE14-tasklist-export-check-20070208

work around tasklist lock export harder


(cherry picked from commit 00c5dbfd048e31a653de0e1cf37d45d539e0c755)
---
 acinclude.m4               |  4 ++++
 src/afs/LINUX/osi_module.c |  6 +++---
 src/afs/LINUX/osi_probe.c  |  2 ++
 src/afs/afs_osi.c          | 11 ++++++++++-
 src/cf/linux-test4.m4      | 14 ++++++++++++++
 5 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/acinclude.m4 b/acinclude.m4
index 40d0e3207..5ebd73085 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -626,6 +626,7 @@ case $AFS_SYSNAME in *_linux* | *_umlinux*)
 		 LINUX_SCHED_STRUCT_TASK_STRUCT_HAS_EXIT_STATE
 		 LINUX_SCHED_STRUCT_TASK_STRUCT_HAS_TGID
 		 LINUX_SCHED_STRUCT_TASK_STRUCT_HAS_TODO
+		 LINUX_EXPORTS_TASKLIST_LOCK
 		 LINUX_GET_SB_HAS_STRUCT_VFSMOUNT
 		 LINUX_STATFS_TAKES_DENTRY
 		 LINUX_FREEZER_H_EXISTS
@@ -840,6 +841,9 @@ case $AFS_SYSNAME in *_linux* | *_umlinux*)
 		 if test "x$ac_cv_linux_fs_struct_fop_has_flock" = "xyes" ; then
 		  AC_DEFINE(STRUCT_FILE_OPERATIONS_HAS_FLOCK, 1, [define if your struct file_operations has flock])
 		 fi
+		 if test "x$ac_cv_linux_exports_tasklist_lock" = "xyes" ; then
+		  AC_DEFINE(EXPORTED_TASKLIST_LOCK, 1, [define if tasklist_lock exported])
+		 fi
                 :
 		fi
 esac
diff --git a/src/afs/LINUX/osi_module.c b/src/afs/LINUX/osi_module.c
index 5103fa810..28376d64a 100644
--- a/src/afs/LINUX/osi_module.c
+++ b/src/afs/LINUX/osi_module.c
@@ -423,7 +423,7 @@ get_page_offset(void)
     struct task_struct *p, *q;
 
     /* search backward thru the circular list */
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,0)
+#if defined(EXPORTED_TASKLIST_LOCK) 
     read_lock(&tasklist_lock);
 #endif
     /* search backward thru the circular list */
@@ -433,14 +433,14 @@ get_page_offset(void)
     for (p = current; p; p = p->prev_task) {
 #endif
 	if (p->pid == 1) {
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,0)
+#if defined(EXPORTED_TASKLIST_LOCK) 
 	    read_unlock(&tasklist_lock);
 #endif
 	    return p->addr_limit.seg;
 	}
     }
 
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,0)
+#if defined(EXPORTED_TASKLIST_LOCK) 
     read_unlock(&tasklist_lock);
 #endif
     return 0;
diff --git a/src/afs/LINUX/osi_probe.c b/src/afs/LINUX/osi_probe.c
index c2d3ce4a1..f83767cb9 100644
--- a/src/afs/LINUX/osi_probe.c
+++ b/src/afs/LINUX/osi_probe.c
@@ -247,7 +247,9 @@ extern asmlinkage long sys_exit (int) __attribute__((weak));
 extern asmlinkage long sys_open (const char *, int, int) __attribute__((weak));
 #endif
 extern asmlinkage long sys_ioctl(unsigned int, unsigned int, unsigned long) __attribute__((weak));
+#if defined(EXPORTED_TASKLIST_LOCK) 
 extern rwlock_t tasklist_lock __attribute__((weak));
+#endif
 
 
 /* Structures used to control probing.  We put all the details of which
diff --git a/src/afs/afs_osi.c b/src/afs/afs_osi.c
index 4fb288d22..a409f0f0d 100644
--- a/src/afs/afs_osi.c
+++ b/src/afs/afs_osi.c
@@ -811,13 +811,18 @@ void
 afs_osi_TraverseProcTable()
 {
 #if !defined(LINUX_KEYRING_SUPPORT)
-    extern rwlock_t tasklist_lock __attribute__((weak));
     struct task_struct *p;
 
+#ifdef EXPORTED_TASKLIST_LOCK
+    extern rwlock_t tasklist_lock __attribute__((weak));
+
     if (&tasklist_lock)
        read_lock(&tasklist_lock);
+#endif
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+#ifdef EXPORTED_TASKLIST_LOCK
     else
+#endif
 	rcu_read_lock();
 #endif
 
@@ -844,10 +849,14 @@ afs_osi_TraverseProcTable()
 	afs_GCPAGs_perproc_func(p);
     }
 #endif
+#ifdef EXPORTED_TASKLIST_LOCK
     if (&tasklist_lock)
        read_unlock(&tasklist_lock);
+#endif
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+#ifdef EXPORTED_TASKLIST_LOCK
     else
+#endif
 	rcu_read_unlock();
 #endif
 #endif
diff --git a/src/cf/linux-test4.m4 b/src/cf/linux-test4.m4
index 0fd4e3ce4..3862c48b9 100644
--- a/src/cf/linux-test4.m4
+++ b/src/cf/linux-test4.m4
@@ -1,3 +1,17 @@
+AC_DEFUN([LINUX_EXPORTS_TASKLIST_LOCK], [
+  AC_MSG_CHECKING([for exported tasklist_lock])
+  AC_CACHE_VAL([ac_cv_linux_exports_tasklist_lock], [
+    AC_TRY_KBUILD(
+[
+#include <linux/sched.h>],
+[
+extern rwlock_t tasklist_lock __attribute__((weak)); 
+],
+      ac_cv_linux_exports_tasklist_lock=yes,
+      ac_cv_linux_exports_tasklist_lock=no)])
+  AC_MSG_RESULT($ac_cv_linux_exports_tasklist_lock)])
+
+
 AC_DEFUN([LINUX_CONFIG_H_EXISTS], [
   AC_MSG_CHECKING([for linux/config.h existance])
   AC_CACHE_VAL([ac_cv_linux_config_h_exists], [
-- 
2.39.5